What information is needed to quote corrugated steel roofing sheets?

An accurate corrugated steel roofing sheet quotation depends on more than the roof area. The specification must identify the steel’s thickness, coating, finish, roof build-up, ancillary components and whether the requirement is for materials only or a complete installation package. These details determine both the quantity of usable sheet and the components needed to form a weather-resistant roof.

Material specification

• Steel thickness: the required gauge or thickness should be stated where it is known. This can depend on the span between supports, the design conditions and the structural specification.
• Coating and corrosion environment: the quotation should record the proposed metallic coating and any paint finish. A building in an exposed rural, industrial or coastal environment may need a different coating consideration from one in a relatively sheltered location.
• Finish and appearance: the selected colour, gloss level and whether the sheets are intended to match existing cladding should be confirmed before ordering.
• Roof build-up: state whether the sheets are being used as a single-skin roof, as part of an insulated composite arrangement or over another supporting layer. The build-up affects the associated components and fixing arrangement.

Information about the building’s use

The building’s purpose is relevant to the specification. An agricultural store, workshop, industrial unit and equestrian building may have different requirements for condensation control, ventilation, internal conditions and resistance to the surrounding environment. Information about machinery, livestock, stored goods or processes inside the building can therefore help establish whether a basic sheet specification is appropriate or whether additional roof design considerations should be allowed for.

It is also useful to identify whether the roof is new or replacing an existing covering, and whether the supporting structure is steel, timber or another material. If the work involves an existing building, the condition and capacity of the supporting members may need to be checked separately rather than assumed from the roofing measurements alone.

Roof geometry and detailing

A quotation is more reliable when it shows how the roof is formed rather than providing only a total area. Eaves, verges, ridges, abutments, changes in roof level, rooflights and penetrations can all affect the sheet take-off and the way the roof is detailed. The roof pitch is particularly important because it influences drainage, sheet suitability and the treatment of laps.

Marking openings for flues, vents, rooflights, access hatches or other equipment is important. If these are omitted at quotation stage, the final order may require additional cutting, replacement sheets or separate detailing. The same applies to unusual roof shapes, parapets and connections to walls or adjacent roofs.

Supply and installation scope

The quotation should clearly distinguish between a supply-only building kit and a package that includes erection. For supply-only work, confirm who will unload, store and install the sheets and who will provide any access equipment. For an erection package, information about ground conditions, site access, working space, overhead obstructions and the readiness of the supporting frame can affect planning and cost.

Site photographs, a simple marked-up plan and sections through unusual junctions can be useful when a physical inspection is not available. They should show constraints such as narrow entrances, adjoining buildings, overhead cables or restricted unloading areas. These practical details do not change the sheet specification itself, but they can affect how the materials are handled and installed.

What the quotation should clarify

• Whether the price covers roofing sheets alone or a complete roof package.
• Whether flashings, closures, fixings, sealants, rooflights and ventilation items are included or excluded.
• Whether cutting, drilling and special trims are allowed for.
• Whether installation, unloading, access equipment and removal of an old covering form part of the scope.
• What assumptions have been made about the supporting structure and finished roof levels.
• Whether any structural calculations, planning information or building-control requirements are to be provided separately.

Before manufacture, the quotation should be checked against the latest roof information and the intended installation method. Changes to the roof shape, openings, coating, sheet length or scope after this point can alter the required materials. Providing a complete specification at the outset gives the supplier a sound basis for confirming the sheet take-off and producing a quotation that can be compared properly with other proposals.